Carburetor for internal-combustion engines



F. H. RQYQE CARBURETOR FOR INTERNAL COMBUSTION ENGINES Filed May 14, 1924 .ff-*finalecF/cnV HENRY FPO VCE.

Patented Apr. 28,A 1925.

UNITED .STATES y 1,535,860 PATENT oFFicE.

FREDERICK HENRY ROYCE, OF DERBY, ENGLAND, ASSIGNOR TO ROLLS ROYCE LIMITED, OF DERBY, ENGLAND.

CARBURETOR'IFOR INTERNAL-COMBUSTION ENGINES.

Application led May 14, 1924. Serial No. 713,f237.

To all whom di may concern:

Be it known that I, FREDERICK HENRY ROYCE, a subject of, the King-` of Great. Britain and Ireland, residing Y at Derby, England, have invented certain new and useful Improvements in Carburetors ,for'In termal-Combustion Engines, of which the following is a specification. s

This invention comprises an improve carburetor for liquid fuel for internal eom bastion engines and has for its object to' serfect and regular Carburation and a more intimate and thorough mixture ofthe fluid and air for all engine speeds und `throttle openings than are attained by all or many of vthe carburetors heretofore in use.

In a carburetor constructed according to my invention, the nozzle is eone'ntrieally located in a cylindrical tube or chamber and has a comparatively wide head. ',The oriecs from which the'fuel is 'sucked are radially arranged around thehead on the line ot' its largest circumference, and around the nozzle is positioned an automatically and vertically' moving choke tube fitting and sliding in the said cylindrical chamber, said choke tube being internally hulged in Wards on a suitable curve or contour to bring about the following conditions, viz:

\ firstly, 'from each end of its internal diameter it is gradually contracted to a point or plane which, when the choke'tube is at the lowest position of its permitted movement, coincides with the plane of thewidest part of the nozzle; secondly, at such point or plane the diameter is ,of such dimension that there is onlyJ a small'elearance between the choke member and the nozzle; and thirdly, on the liftingof the choke tube the passageway between it and the nozzle is gradually opened and enlarged to admit the required air. y p

The nozzle is also provided with an automatic valve which controls-the passageway of 'thefuel from the minimum to the maximum required, the automatic control of the choke tube and that of the valve be ing broughtabot by'means of the vacuum created by the engine.

lVith this construction, I am able to pro vide that in all positions the narrowest part of the airway and hence the part in which the air is traveling at the greatest velocity is across themouth of the orifices of the nozzle. Further, by means ofi such a choke vtube and of a suitably shaped diaphragm chamber, and to shape and suitably restrictA the pathway through the ports of, said spraying chamber into the throttle, chamber to facilitate the mixing of fuel and air and to maintain a rapid inw, thus preventing condensation and deposit of fuel.

Preferably, I adopt the form of nozzle commonly known as a 4diffuser nozzle; that is to say, a nozzle which opens into a chamber under suction ot' the engine and with which air holes also communicate, the fuel and air mixing together in the chamber and being drawn out through suction passages by the engine.4

In the accompanying drawings is shown' an example Vof my invention, Fig. 1 being a sectional central elevation and Fig, 2 ai like section of the nozzle on an enlarged scale.

In said drawings a indicates a horizontal cylindrical member open atene end a1 to constitute the air inlet, said cylindrical member having an opening at its upper side from the edges of which projects ythe upstanding part a2 and a suitablyshapcd opening on the lower side to receive and locate the fixed portion of the nozzle hereinafter described.

b indicates a cylindrical member formed with an extension b1 fitting into the upstanding part a2, and b2 indicates an enlarged part of the member b, closed by an air-tight cover b3 secured by a nut b{engag ing a thread on the part Z22 (hereinafter called the piston chamber). l Z222 indicates a row of holes to admit air under atmospheric pressure, and b5 is an enlarged part ot-the member b which constitutes the throttle chamber.

c indicates the throttle tube (also shown extended by broken lines at c1 to illustrate the throttle .valve c?) branched from, and its walls merging with the Walls of the part b5.

d indicates e, cylindrical member sliding in the member b and Which constitutes the y and attached to`the walls oipart d1, this part and the said diaphragm constituting a piston sliding in the piston chamber o2. cl3

indicates an annular groove and Zt arow of holes formed in and through the Wall of the part (Z1, whilst Z5 represents a hole through. the diaphragm. d indicates smaller annu'- lar grooves in the wall of the part d1 (the function of the various grooves being set t'orth hereinafter), Z7 a spiral spring acting between the cover b3 and the diaphragm cl2, a a diaphragm extending across, and attached to, the member (l-this diaphragn'i being curved upwards and outwards from the centre and so placed that when said member (l is at itsl lower` limit of movement, the diaphragm istjust above the lip of the enlarged part of. tl" indicates a circumferential row of holes through ther wall ot' the member (Z, d10 elliptical holes through the wall of and equi-slmced around member d, and ci a part. oflthc member al with its interior circumference bulged inwards on a suitable curve to form the choke tube. '.lhe bore ot' the choke tubo dl'has a small portion ot' its wall, indicated at d (Fig. '2), which is substantially parallel with the axis ot' the bore, so

.as to enable an initial lifting movement oi the clement el Without an)v substantial Aenlargement of the space between such element and the nozzle outlets. i

The nozzle consists of three parts, coniprising the tubular elements A., B, C; and cooperating therewith is a fuel y'alve e which moves with the piston diaphragm Z2 and has formed on it three taper grooves e422 which bridge a restriction D in the fuel H conduit. The outer part C of the nozzle is movable by the operator, ashereinafter ex? plained,'and comprises the tubular element or sleeve c3, which is ormed with a widened v part 631, attlie outer edge of which 'are the spray openings c. ct indicates am elongated tubular member or sleeve l passing through a hole in the diaphragm al, said sleeve e* being connected to the valve c2 at one end and to a threaded rod c at-the other end byball-and-socliet joints. The threaded rod c5 passes through a h ole'in the diaphragm Z2 and is secured by nut and lock nut cB and c7, respectively. c8 indicates bushings through which the valve c2 slides,

and e9 indicates a helical spring adapted to keep thefjoint` sockets in position and avoid any s lackness.

f designates the float tank, and g' a rod or pinion Which'v (Within limits) caribe rotated hy the operator through suitable connections (not shown) and having axial serrations about its periphery which Aen age teeth formed on the part @sof the nozz e.

The operation of. the carburetor is as follows O11 the engine being turned over, the partial-vacuum 'createdin the throttle chamber is communicated via' the holes d to the space within the sliding piston member al, and thence via the holes d* and annular Lacasse groove Il and the clearance betwee vthe parte al and b2, and also via the hole d5 in the diaphragm d2, to the piston chamber above said diaphragm. Thereupon the Litmospheric pressure operating through the holes 522 will lift the member d whereby the air pijissageivay adjacent the spray openings cg will be enlarged. At the same tixue the. depression Will be communicated via the holes d to the spraying chamber and a culrent o-t' air mill be sucked past the nozzle at high velocity, the most restricted part ot theair passage being that in'nnodiatcly adjacent the nozzle outlets.- As the member (l rises,

the passage through the holes dm to the 8 0 The shape of the tube, the spraying chamber, diaphragm 'd8 90 and ports d10 with their openings into the throttle chamber secure a restricted passagev from the spraying chamber to the throttle chamber and hence a'rapid tlow with a consequential inhibition ot condensation and Si deposit of fuel. By means of the pinion g the operator can raise or lower the nozzle sleeve c; such movement ot the part c producing` as a result thereof, the movement of the choke tube d and valve rod c in the same direction, the position of the grooves c2 in said rod relative to the restriction D being' consequentlyY varied. so that the richness of the mixture supplied is thus controlled Within limits. This movement of the choke tube andvalve rodat the same time and in the same direction as the sleeve C is due to the fact th t the movement of said sleeve brings its si'ay orifices egg-nearer to the Wall of the dholre tube (assuming that the 4sleeve is moved upward) and, in consequence, rcstribts the dir space or passage between the peripheral edge of the part c31- of the sleeve wherein saidorilices are formed and the aforesaid choke tube Wall, ,'lhis, as will be apparent, intensities the vacuum in fthe throttle chamber and, hence. on the top ot the piston, with the result that thai latter rises, carrying With it the choke tube and the valve rod` so that the positionof said parts relative to sleeve C is thereby restored. The reverse takes place when the sleeve is lowered, as Will be understood.

What I claim'as my invention and desire to secure by' Letters Patent ot the United' States is 1. A carburetor` comprising an outer cylindrical member provided with an enlarged cincurntei'ential.I portion constituting a throttle chamber and having a fuel nozsla therein, andan inductionfpipe communicating with such portion; an inner cylindrical member slidable in the outer member and formed with circumferential ports which, according to the relative positions of thetwo members, oplen more or less 'into said chamber; a diap ragm in the inner member above said ports; and means whereb the psition of the inner member within t e outer memberA is automatically adjusted by the I degree of vacuum in the throttle chamber.Y

2. A. carburetor, comprising an outer cylindrical member provided with an enlarged circumferential portion constituting a throttle chamber and having a full nozzle therein, and an induction pipe communicating with such portion; an inner cylindrical member slidable in the outer member and formed with upper and lower series of circumferential` ports, the upper series opening constantly into said chamber, and the lower series opening more or less thereinto accordingtothe relative positions of the -two members; a diaphragm in the inner ner tubular member, a rod movable axially through said member to control the Supply of fuel thereto, and an outer tubular member telescoped on the inner tubular member and having spray outlets for the fuel delivered thereto from the latter member; means for raising and loweringsaid rod and said choke tube; and se arate means for adjusting the position of t 1e outer tubular member on the inner tubular member relatively to the same and to thechoke tube.

4. In' a carburetor, the combination of a choke tube; a nozzle comprising a fixed, in .ner tubular member, a rod movable axially through said member to control the supply of fuel thereto, and an outer tubular member telescoped on the inner tubular member and having spray outlets for the fuel delivered thereto from the latter member; suction-controlled means for automatically adjusting the position of said rod within the inner tubular member; andananually-controlled means for independently adjusting the' position of the outer tubular member on the inner' tubular member relatively tothe same and to the choke tube.

' 5. A carburetor, comprising an outer cy.

lindrical body member; an inner cylindrical member slidable therein, having its lower portion shaped to form a choke tube and communicating with the air'inlet; a nozzle with whichv the choke tube is associated; a throttle chamber in communication with the outer member; and a suction-actuated diaphragm carried by the upper portion of the inner member for controlling the sliding movementsH of that member, the portion or' saidinner member between the diaphragm and the choke tube being provided with circumferential ports for adjustably control ling communication between the interior of the inner member and the throttle chamber, to regulate the passage of fuel mixture trom. the said inner member to the throttle chamber. l .i

6. A carburetor for internal combustion engines, comprising an outer cylindrical body member Vhaving a lcircnint'erentiallyenlarged portion constituting a .throttle chamber from which the induction pi e to the engine is branched; an inner cylin rical member slidable in the outer member having its lower portion shaped toi/form a choke (iii tube and communicating with the air inlet;

a nozzle with which the choke tube is associated; and a suction-actuated diaphragm carried by the upper portion ofthe inner member for controlling the sliding movements of -that member, the portion of said inner member between the diaphragm and the choke tube being provided withI eircomferential ports which open more or less fully into said throttle chamber according to the position of the inner member, to regulte the passage of fuel mixture from the said inner member to the throttle chamber. i

7. A carburetor for internal combustion engines, comprising, in combination, a dii? fuser nozzle; a cylindrical body member wherein 'the nozzle is concentrically arranged; a throttle cb amber; a valve for conm trolling the supply .of fuel to said' nozzle, a choke tube concentrically and slidably arranged in said body member and encircling the head of the nozzle, thecross-sectionalv area of the choke tube at its narrowest part equaling except for a very small, clearance the cross-sectional area of the broadest part of said nozzle head, such narrowest and broadest parts lying,` in the same plane when the engine is at rest, and said choke Atube widening out from said plane in both directions and providing through it the only air supply; and a single means for controllingl the position of the choke tube and the fuel valve.

In witness' whereof I have this specication.

rnnnnmoir HENRY norcia lim 

